A212142 Number of (w,x,y,z) with all terms in {1,...,n} and w >= (geometric mean of x,y,z).

0, 1, 9, 45, 145, 351, 729, 1345, 2307, 3702, 5650, 8271, 11736, 16174, 21774, 28719, 37210, 47457, 59703, 74170, 91116, 110796, 133498, 159525, 189246, 222880, 260835, 303465, 351103, 404109, 462969, 527992, 599664, 678387, 764656

Offset

0,3

Comments

A212142(n)+A212141(n)=n^4. For a guide to related sequences, see A211795.

Links

Table of n, a(n) for n=0..34.

Mathematica

t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w^3 >= x*y*z, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 50]] (* A212142  geometric mean *)
(* Peter J. C. Moses, Apr 13 2012 *)

Crossrefs

Cf. A211795.

Sequence in context: A289721 A060008 A212089 * A095166 A357717 A341988

Adjacent sequences: A212139 A212140 A212141 * A212143 A212144 A212145

Keyword

nonn

Author

Clark Kimberling, May 06 2012

Status

approved